This proposal involves an analysis of the role of cellular factors in the immune response of mice to Capillaria hepatica, a nematode whose life cycle and developmental stages are localized in the liver. An assessment will be made of the role of lymphoid cells and the factors which regulate the cellular composition of granulomas formed around the parasite egg, since in this, and other helminth systems, the egg has been demonstrated to be of importance in hepatic granulomas. The kinetics of cell mobilization and recruitment at the local site of parasitism will receive attention with particular reference to the relative role played by T and B cells in the initiation and resolution of granuloma formation. Four major areas of investigation are proposed, within which several subdivisions will be considered: (1) In vivo studies on affector cell function by passive transfer of "educated" lymphoid cells to define the origin of cells contributing to granuloma formation. (2) In vitro studies on effector cell function by qualitative and quantitative assessments of expression of cell mediated immunity during granuloma formation. (3) Qualitative and quantitative studies of the humoral and cellular factors responsible for the lack of egg destruction following granuloma resolution. (4) Determination of the granuloma sensitizing factor(s) by antigenic analysis and assessment of active antigen fractions.